This invention relates to turbines in general and more particularly to an improved device for controlling a steam or gas turbine.
A device for controlling a steam or gas turbine, including a valve beam for actuating at least two control valves, the valve cones of which are hung by their valve stems in the valve beam and are held by lifting heads, is described in German Pat. No. 760 185. The valve beam is provided with holes in which the valve stems of two or more control valves slide. In this design, the valve stems are held by lifting heads in the form of nuts. To open the control valves, the valve beam located above is lifted, for instance, by a lever linkage and a servo motor. The control valve with the lowest lifting head opens first, then the one with the next higher lifting head, etc. until all control valves are open. For closing the control valves, the valve beam is lowered whereby the steam or gas pressure present pushes the individual valve cones tightly onto the corresponding valve seats as soon as the seats are reached.
In the known device the pulsating forces acting on the valve cones are transmitted to the valve beam via the valve stems and the lifting heads in the form of nuts, and, in the screw connections between the valve stems and the lifting heads, the forces are deflected by an angle of 180.degree.. Due to this deflection of the forces, the fatigue stength of the screw connections is extremely low, so that breaks frequently occur in the region of the first load carrying thread of the valve stems.
In another known device for controlling a steam or gas turbine, a split valve beam is provided so that the control valves with valve cone, valve stem and lifting head can be made in one piece. This design with the lifting head integrally formed in the valve stem has the advantage that the weakening by a screw connection is eliminated, but splitting of the valve beam must be tolerated instead.
It is therefore an object of the present invention to provide a device for controlling a steam or gas turbine, in which, on the one hand, the fatigue strength at the lifting heads is increased and in which, on the other hand, the valve beam can be constructed without being split.